Ben Affleck is an unhappy math genius who’s moonlighting as a gun for hire in the first teaser trailer for Warner Bros.’ “The Accountant.”

The tension-filled teaser shows he’s playing both a small-town accountant and freelance assassin without friends, then indicates that he was diagnosed with a developmental disorder as a child.

“Can our son ever be normal? Define normal,” the voiceover asks. “Maybe he’s capable of much more than we know.”

Anna Kendrick, J.K. Simmons, Jon Bernthal, Jeffrey Tambor and John Lithgow also star. The film is directed by Gavin O’Connor from a screenplay by Bill Dubuque.

The official synopsis: “Christian Wolff (Affleck) is a math savant with more affinity for numbers than people.  Behind the cover of a small-town CPA office, he works as a freelance accountant for some of the world’s most dangerous criminal organizations.  With the Treasury Department’s Crime Enforcement Division, run by Ray King (J.K. Simmons), starting to close in, Christian takes on a legitimate client: a state-of-the-art robotics company where an accounting clerk (Anna Kendrick) has discovered a discrepancy involving millions of dollars.  But as Christian uncooks the books and gets closer to the truth, it is the body count that starts to rise.”

Simmons explains in the teaser that Wolff has the smarts to steal millions from the Sinaloa drug cartel and get out alive. “Imagine the secrets this guy has,” he adds.

“The Accountant” is set to hit theaters on Oct. 14.